applied fracture mechanics

90Applied Fracture MechanicsThis result corresponds to a classic one in Fracture Mechanics, which is the general casevalid for brittle materials as glass and ceramics.7. Experimental analyses7.1. Ceramic, metallic and polyurethane samplesThe analyzed ceramic samples were produced by Santos [19] and Mazzei [41]. The rawmaterial used for its production was an alumina powder A-1000SG by ALCOA with 99%purity. Specimens of dimensions 52mm 8mm 4mmwere sintered at 1650 °C for 2 hours,showing average 7 mm grain sizes. Their average mechanical properties are shown in Table1 with elastic modulus E = 300 GPa and rupture stress 340MPa.The analyzed metallic samples were multipass High Strength Low Alloy (HSLA) steel weldmetals and standard DCT specimens. HSLA are divided in two groups based on thewelding process utilized and the microstructural composition. The first group (A1 and A2welds) is composed of C-Mn Ti-Killed weld metals and were joined by a manual metal arcprocess. The second group (B1 and B2 welds), joined by a submerged arc welding process, isalso a C-Mn Ti-Killed weld metal, but with different alloying elements added to increase thehardenability. Mechanical properties of both welds and DCT metals are listed in Table 1.fMaterial Samplef E(MPa) (GPa) JIC(exp)(KJ/m2 )L0C(exp)(mm) KIC (MPa.m 1/2 ) H (exp)Ceramic Alumina 340 300 0,030 0.4956 424,2477056 0,7975 0,0096MetalsPolymersA1CT2 516,00 1,34 291,60 0,48256 635,3313677 0,71 0,01A2SEB2 537,00 3,63 174,67 0,36264 573,1747828 0,77 0,01B1CT6 771,00 16,64 40,61 0,22634 650,1446157 0,77 0,02B2CT2 757,00 1,96 99,22 0,26553 691,3971955 0,58 0,05DCT1 554,001,7197 227,00 0,40487 624,8021278 -DCT2 530,001,6671 211,47 0,3995 593,7576222 -DCT3 198,750,3902 318,00 1,00000 352,2752029 -PU0,5PU1,040,70 0.8 0.040,70 0.8 0.08,10 0,29951 39,47980593 0,47 ± 0,073,00 0,23685 35,10799599 0,50 ± 0,05Table 1. Data extracted from experimental testing of J-R curves obtained by compliance method.The analyzed polymeric samples are a two-component Polyurethane, consisting of 1:1mixture of polyol and prepolymer. The polyol was synthesized from oil and the prepolymerfrom diphenyl methane diisocyanate (MDI). Their mechanical properties are shown in Table 1.